1. WSL Swiss Federal Research Institute; 8903 Birmensdorf Switzerland
2. Fachbereich Biologie; Philipps-Universität Marburg; 35032 Marburg Germany
3. UMR1202 Biodiversity, Genes & Communities; INRA Pierroton; 33612 Cestas Cedex France
4. ALTERRA Centre for Ecosystem Studies; Wageningen UR; 6700 AA Wageningen The Netherlands
5. UMR “Interactions Arbres/Micro-Organismes”; INRA Nancy; 54280 Champenoux France
6. Institute of Soil Ecology; Helmholtz Zentrum München; 85764 Neuherberg Germany
7. Institute for Forest Genetics; Johann Heinrich von Thuenen-Institute; 22927 Grosshansdorf Germany
8. Plant Research International; Wageningen UR; 6700 AA Wageningen The Netherlands